It's because you have #N/A errors in col C, try this instead
Formula: copy to clipboard 
=IFERROR(INDEX('Punch Log'!$F$2:$F$463,AGGREGATE(15,6,(ROW('Punch Log'!$F$2:$F$463)-ROW('Punch Log'!$F$2)+1)/('Punch Log'!$C$2:$C$463=P1)/('Punch Log'!$D$2:$D$463=O1),ROWS($Q$1:$Q$1))),"")